Passive display screens are used to present images that are projected by a projector. Home entertainment systems often use projection systems to project images onto a passive screen to provide a big screen, high quality viewing experience.
Such screens may also be used in augmented reality environments where users interact with real-world objects and virtual or computer-generated objects and information. These environments may be created, for example, in a room equipped with computerized projection and imaging systems that enable presentation of images on various objects within the room and facilitate user interaction with the images and/or objects. The augmented reality may range in sophistication from partial augmentation, such as projecting a single image onto a surface and monitoring user interaction with the image, to full augmentation where an entire room is transformed into another reality for the user's senses. The user can interact with the environment in many ways, including through motion, gestures, voice, and so forth.
Detecting user interaction with projected images onto objects or surfaces, such as a projection screen, can be challenging in augmented reality environments. Depth cameras are often used to ascertain distance from the camera to the projection surface so that the images can be accurately projected. The depth camera also attempts to capture movement of the user's hand (or other portions of the body) when interacting with the projected images. In particular, detection of user touch via a fingertip on a projected image poses difficulties for depth cameras, particularly when the user's fingertips are in close proximity to the reference surface. Because of inherent depth resolution and depth measurement noise of the camera, there exists a noise floor, under which the object's depth image diffuses into the background and digital separation of the two is difficult.
As augmented reality systems continue to evolve, there is a continuing need for improved performance of such systems. In particular, there is a need for improved techniques to accurately detect user interactions, particularly through touch, with projected images.